The present invention relates generally to the field of safety exit doors, and locking mechanisms therefor.
It has heretofor been known generally to provide panic exit doors with top and bottom conventional reciprocably mounted bolts which are arranged to be normally maintained in an extended bolted position, when the door is closed. In the known structures, the bolts are arranged to be actuated by a panic actuator device mounted on the inside of the door for emergency operation to move the top and bottom bolts to retracted release position so as to enable the door to be swung to an open position.
Such structures are disclosed, for example, in U.S. Pat. Nos. 3,334,500 and 3,663,047, and which, according to the prevailing usual practice, utilize reciprocably mounted top and bottom bolts that are carried by the door structures, these bolts being arranged to enter keeper recesses in the door frame header and the threshold structures.
While bolts of the reciprocable type are well suited for locking mechanisms on conventional doors, it has been found that in the case of panic exit doors excessive and undesirable operating loads may develop under certain conditions. In panic exit door installations, crowding of persons at the door during uncontrolled panic conditions may result in the application of abnormally high pushing forces against the inside of the door, and as a result high friction load forces on the bolts may indeed be so great as to seriously affect, and under some conditions make it virtually impossible to retract the bolts by operating the panic bar actuating device on the inside of the door.
The present invention proposes to solve this difficulty by providing a simplified and unique lock mechanism by reducing the number of reciprocably mounted bolt structures. Instead, only one reciprocable bolt is provided at the bottom of the door, and at the top of the door a fixed header bolt is utilized for controlling an associated releasable latching means which can be dogged in a latched position with respect to the top bolt, and which is also used to effectively dog the bottom bolt in its retracted position. In the present invention, the bolt mechanisms and their connections to the actuators, as well as the elements for dogging the bolts, are all mounted and concealed within the stile frame member at the swinging edge of the door in a manner which permits greater flexibility and adaptation of actuating devices which may embody a key-controlled lock cylinder as well as panic bar actuator devices.